When faced with a dilemma between believing what is supported by an impartial assessment of the evidence (e.g., that one's friend is guilty of a crime) and believing what would better fulfill a moral obligation (e.g., that the friend is innocent), people often believe in line with the latter. But is this how people think beliefs ought to be formed? We addressed this question across three studies and found that, across a diverse set of everyday situations, people treat moral considerations as legitimate grounds for believing propositions that are unsupported by objective, evidence-based reasoning. We further document two ways in which moral considerations affect how people evaluate others' beliefs. First, the moral value of a belief affects the evidential threshold required to believe, such that morally beneficial beliefs demand less evidence than morally risky beliefs. Second, people sometimes treat the moral value of a belief as an independent justification for belief, and on that basis, sometimes prescribe evidentially poor beliefs to others. Together these results show that, in the folk ethics of belief, morality can justify and demand motivated reasoning.
From the General Discussion
5.2. Implications for motivated reasoning
Psychologists have long speculated that commonplace deviations from rational judgments and decisions could reflect commitments to different normative standards for decision making rather than merely cognitive limitations or unintentional errors (Cohen, 1981; Koehler, 1996; Tribe, 1971). This speculation has been largely confirmed in the domain of decision making, where work has documented that people will refuse to make certain decisions because of a normative commitment to not rely on certain kinds of evidence (Nesson, 1985; Wells, 1992), or because of a normative commitment to prioritize deontological concerns over utility-maximizing concerns (Baron & Spranca, 1997; Tetlock et al., 2000). And yet, there has been comparatively little investigation in the domain of belief formation. While some work has suggested that people evaluate beliefs in ways that favor non-objective, or non-evidential criteria (e.g., Armor et al., 2008; Cao et al., 2019; Metz, Weisberg, & Weisberg, 2018; Tenney et al., 2015), this work has failed to demonstrate that people prescribe beliefs that violate what objective, evidence-based reasoning would warrant. To our knowledge, our results are the first to demonstrate that people will knowingly endorse non-evidential norms for belief, and specifically, prescribe motivated reasoning to others.
Our findings suggest more proximate explanations for these biases: That lay people see these beliefs as morally beneficial and treat these moral benefits as legitimate grounds for motivated reasoning. Thus, overconfidence or over-optimism may persist in communities because people hold others to lower standards of evidence for adopting morally-beneficial optimistic beliefs than they do for pessimistic beliefs, or otherwise treat these benefits as legitimate reasons to ignore the evidence that one has.